These are the reasons why they asted so long xx
• Barbed wire - Difficult to cut
• Machine guns - mowed down men with intersecting crossfire
• Gas - Slowed down heavily-laden attackers. Not so affective in trenches.
• Shells - saved soldiers from all but a direct hit. Churned up the ground. Destroyed drainage systems and made attack difficult.
• Railway - Could rush reinforcements to a threatened spot very quickly .
• Lack of secrecy - Enemy could easily see when extra supplies were brought up for an attack
• Attack at walking pace - Men could only advance at walking pace
• Lack of experience - Generals never fought this way before and couldn't think of ways of breaking through trenches
• Zigzagging trenches - Used to stop the enemy artillery destroying a whole line of trench and to prevent successful attackers being able to fire along a long length of a trench
• Communication Trenches - Joined lines of trenches
• Blind alleys - Lead nowhere, used to confuse an enemy and sow them down in the event of a successful attack.
• Forward Positions - were built for miners and snipers
• Underground "saps" - tunnels driven under enemy trenches so that explosives could be placed under them and detonated.
• No Man's Land - Difficult to cross as belts of barbed wire, shell holes and very swampy conditions when it rained
hope this helped! (: